Sheet take-out apparatus with gap counter

ABSTRACT

A sheet take-out apparatus includes a first separation unit, a second separation unit, a drawing roller for drawing sheets from a nip of the second separation unit, and a pinch roller rotating in contact with it. Overlapping sheets which pass the first and second separation units and are not separated are detected to be overlapped in a state that they are clamped by the nip of the drawing roller and pinch roller. When overlapping is detected, in a state that the rear ends of the overlapping sheets in the conveying direction are restricted by the nip, the drawing roller and pinch roller are stopped and the overlapping sheets are re-separated.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a divisional of co-pending U.S. patentapplication Ser. No. 11/175,216 filed on Jul. 7, 2005 for which priorityis claimed under 35 U.S.C. §120. This application also claims priorityunder 35 U.S.C. §119(a) on Japanese Patent Application No. 2004-203429filed in Japan on Jul. 9, 2004. The entire contents of each of theseapplications are herein fully incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a sheet take-out apparatus and a sheettake-out method for separating and taking out a plurality of sheets oneby one onto a conveying route.

DESCRIPTION OF THE BACKGROUND

Conventionally, for example, as described in Japanese Patent ApplicationPublication No. 2003-81461, as a sheet take-out apparatus, an apparatusincluding a feed-out roller rotating in contact with a sheet at one endin the stacking direction, thereby feeding out the concerned sheet, atake-out roller for rotating in contact with the fed-out sheet, therebytaking out the concerned sheet on a conveying route, a separation rollerfor separating sheets pressed to the take-out roller via the conveyingroute and given separation force in the reverse direction, therebyoverlapped, and a conveying roller for conveying sheets passing a nipbetween the take-out roller and the separation roller is known.

In this apparatus, when a sheet conveyed by the conveying roller isdetected, the take-out roller is rotated reversely, thus overlappingsheets can be easily separated by the separation roller.

However, in this apparatus, overlapping sheets which cannot be separatedby the separation roller are conveyed straight to the later stage ofprocessor via the conveying roller. The sheets conveyed in theoverlapping state cause jamming in conveyance.

Therefore, it may be considered to add a re-separation unit forre-separating overlapping sheets passing through the separation roller.However the apparatus constitution is complicated and a new problemarises that the cost of apparatus is increased.

Further, overlapping sheets are generally rejected during conveyance andare removed from processing objects, so that when overlapping of sheetsoccurs, the rejected sheets must be re-supplied and processed. Thus aproblem arises that the processing capacity of the apparatus is reduced.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a sheet take-outapparatus and a sheet take-out method for surely separating overlappingsheets and enhancing the processing capacity.

According to the embodiments of the present invention, the sheettake-out apparatus comprising a take-out unit for taking out a pluralityof sheets in a stacked state one by one on a conveying route, aseparation unit for shifting and separating overlapping sheets taken outon the conveying route in a stacked state by the take-out unit, anoverlapping detector for detecting overlapping sheets not separated bythe separation unit, and a re-separation unit for clamping the rear endsof the overlapping sheets detected by the overlapping detector in theconveying direction to reduce the speed and re-separating theoverlapping sheets is provided.

Furthermore, according to the embodiments of the present invention, asheet take-out method comprising the steps of taking out a plurality ofsheets in a stacked state one by one on a conveying route, shifting andseparating overlapping sheets taken out in an overlapped state on theconveying route at the time of take-out, detecting overlapping sheetsnot separated, and clamping and decelerating the rear ends of theoverlapping sheets detected in the conveying direction and re-separatingthe overlapping sheets is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the schematic structure of the sheettake-out apparatus relating to the embodiments of the present invention;

FIG. 2 is a flow chart for explaining the re-separation operation by thesheet take-out apparatus shown in FIG. 1;

FIG. 3 is a flow chart for explaining the operation of a gap counter;

FIG. 4 is a plan view for explaining the re-separation operation ofoverlapping sheets;

FIG. 5 is a plan view for explaining the re-separation operation ofoverlapping sheets; and

FIG. 6 is a flow chart for explaining the re-separation operationrelating to another embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the embodiments of the present invention will be explainedin detail with reference to the accompanying drawings.

FIG. 1 shows a plan view showing the schematic structure of sheettake-out apparatus 100 (hereinafter, referred to as just take-outapparatus 100) relating to the embodiments of the present invention.Take-out apparatus 100 includes separation and supply portion 1 fortaking out a plurality of sheets P in a stacked state one by one on aconveying route and shifting and separating a plurality of sheets(hereinafter, sheets in this state are referred to as overlappingsheets) taken out in an overlapping state and conveying portion 2 forfurther conveying sheets P fed by separation and supply portion 1 to thelater stage of processor.

Separation and supply portion 1 has two endless floor belts 3 extendingin the stacking direction of a plurality of sheets P. Respective floorbelts 3 are wound and stretched round pulleys, not drawn, installedcoaxially and away from each other along rotary shaft 4, make contactwith the lower end sides of the plurality of sheets P, and support theplurality of sheets P in a standing position. Floor belts 3 are drivenby floor motor 5 and move the plurality of sheets P with the lower endsides in contact with them in the stacking direction.

To floor belts 3, backup plate 6 is attached. Backup plate 6, as floorbelts 3 travel, makes contact with sheets P at the rear end in thestacking direction along the surface and moves all sheets P in thestacking direction. Backup plate 6 is attached slidably along rail 7extending in the stacking direction.

On the other end side of the plurality of sheets P set in the standingposition on floor belts 3 away from backup plate 6 in the stackingdirection, feed-out roller 8 for feeding concerned sheets P upward inthe drawing (the forward direction) by rotating in contact with sheets Pon the other end side is installed. Feed-out roller 8 is rotatablyattached to the front end of arm 15 extending in the stacking directionvia a one-way clutch not drawn. Feed-out roller 8 is connected tofeed-out motor 12 via a plurality of pulleys and a plurality of timingbelts 9, 10, and 11. The one-way clutch not drew functions so as tofreely rotate feed-out roller 8 in the forward direction when pullingout sheets P.

Arm 15 is supported by two support arms 13 and 14 which are parallelwith each other. Namely, to support arm 14 attached to arm 15, twopulleys for winding timing belts 9, 10, and 11 aforementioned areattached. Further, on the other end side of the other support arm 13attached to arm 15 away from arm 15, the rotary shaft of arm motor 16for rotating support arm 13 is connected. Arm motor 16 is a servo motorunder torque control.

When arm motor 16 rotates, two support arms 13 and 14 swing and arm 15moves almost in the longitudinal direction. Namely, by use of suchparallel link mechanism L, arm 15 can be moved in the axial directionthereof and feed-out roller 8 can be pressed almost perpendicularly tosheets P. The pressure of feed-out roller 8 to sheets P is controlledfixed by arm motor 16.

When feed-out motor 12 is rotated in the state that feed-out roller 8 ispressed to sheets P, feed-out roller 8 rotates in the forward directionand sheets P at the end in the stacking direction are fed out. Afterfeed-out of sheets P, floor motor 5 rotates, and floor belts 3 travel,and next sheets P are fed to the take-out position. Further, thecomponents indicated by reference numerals 3, 5, 6, 8, 12, and 16aforementioned function as a take-out unit of the present invention.

On conveying route 101 on the downstream side of feed-out roller 8 inthe conveying direction of sheets P, a plurality of separation units,that is, in this embodiment, two separation units SP1 and SP2 areinstalled away from each other in the conveying direction. Firstseparation unit SP1 on the upstream side in the conveying direction hasfirst feed roller 17 on one side (on the left in the drawing) ofconveying route 101, that is, on the same side as feed-out roller 8 andhas first separation roller 20 at the position opposite to first feedroller 17 on the other side (on the right in the drawing) of conveyingroute 101. Second separation unit SP2 on the downstream side in theconveying direction also has similarly second feed roller 23 and secondseparation roller 26 across conveying route 101. First and secondseparation units SP1 and SP2 have the almost same structure, so thathereinafter, first separation unit SP1 will be explainedrepresentatively, and for second separation unit SP2, only the referencenumerals of the components corresponding to first separation SP1 aredescribed, and the detailed explanation will be omitted.

The rotary shaft of first feed roller 17 (23) is connected to first feedmotor 19 (25) via timing belt 18 (24). First feed roller 17 (23) isattached to the rotary shaft via a one-way clutch not drawn so as togive no load to sheets P when drawing sheets P.

Further, on first feed roller 17 (23), first separation roller 20 (26)is arranged at a fixed pressure via conveying route 101. To firstseparation roller 20 (26), first separation motor 22 (28) is connectedvia timing belt 21 (27). First separation motor 22 (28) is a servo motorunder torque control and gives separation force to first separationroller 20 (26) so as to rotate in the opposite direction of theconveying direction of sheets P.

When overlapping sheets are fed onto conveying route 101 by feed-outroller 8, first sheet P is conveyed in the forward direction by firstfeed roller 17 on the same side as feed-out roller 8, and to the secondand subsequent sheets taken out together with first sheet P, separationforce in the opposite direction is given from first separation roller20, and the overlapping sheets are shifted and separated from eachother. On the other hand, when one sheet P is normally fed ontoconveying route 101 by feed-out roller 8 and when no sheet P exists inthe nip between first feed roller 17 and first separation roller 20,first separation roller 20 rotates following first feed roller 17.

Second separation unit SP2 has the same function as that of firstseparation SP1 mentioned above and functions so as to additionally shiftand separate the overlapping sheets, which cannot be separatedcompletely by first separation unit SP1, from each other.

On the downstream side of second separation unit SP2 in the conveyingdirection, drawing roller 29 and pinch roller 32 arranged opposite todrawing roller 29 so as to from a nip are installed. When sheets areclamped by the nip between drawing roller 29 and pinch roller 32, secondseparation unit SP2 performs an operation of drawing sheets existing inthe nip between second feed roller 23 and second separation roller 26.To drawing roller 29 arranged on one side of conveying route 101,drawing motor 31 is connected via timing belt 30. Pinch roller 32arranged on the other side of conveying route 101 is arranged at a fixedpressure to drawing roller 29 and rotates following drawing roller 29.

Conveying portion 2 includes second conveying roller 33 and firstconveying roller 34 for conveying sheets P fed from separation andsupply portion 1 to the later stage of processor (not drawn). First andsecond conveying rollers 33 and 34 are arranged on the left of conveyingroute 101 in the drawings away from each other in the conveyingdirection and are respectively connected to conveying motor 37 viatiming belts 35 and 36. Conveying motor 37 rotates first and secondconveying roller 33 and 34 in the forward direction.

On second conveying roller 33 on the upstream side in the conveyingdirection, plate spring-shaped guide plate 38 (a compressing member) isarranged opposite to it via conveying route 101. Guide plate 38 isformed by bending a platy member made of resin. Guide plate 38 isattached in a convex posture toward second conveying roller 33 acrossconveying route 101 from the right of conveying route 101 in the drawingand is arranged in a nest shape with a plurality of roller units (notdrawn) of second conveying roller 33. Namely, at the intervals betweenthe plurality of roller units which are arranged at predeterminedintervals, belt-shaped guide plates 38 are respectively arranged. Bydoing this, guide plates 38 can press sheets P conveyed between theguide plates and second conveying roller 33 to second conveying roller33 at weak pressure.

Concretely, guide plates 38 clamp sheets P with clamp force weaker thanthe clamp force of sheets P by drawing roller 29 and pinch roller 32between the guide plates and second conveying roller 33. In other words,guide plates 38, when drawing roller 29 is decelerated or stopped in thestate that sheets P are conveyed by drawing roller 29 and secondconveying roller 33, give clamp force to sheets p so as to decelerate orstop sheets P depending on the rotational speed of drawing roller 29.

At the position on the right of conveying route 101 in the drawing andopposite to first conveying roller 34, pinch roller 39 driven to rotatein contact with first conveying roller 34 is installed. Pinch roller 39is arranged so as to give a fixed pressure to first conveying roller 34via conveying route 101.

Immediately after the nip between drawing roller 29 and pinch roller 32of separation and supply portion 1 mentioned above, first sensor 40 isarranged. First sensor 40 has a light emitting unit and a lightreceiving unit and a light beam emitted from the light emitting unit isreceived by the light receiving unit. Namely, sheets P shield theoptical axis of the light beam, thus the sensor output is turned off,and the first sensor detects passing of sheets P. Further, immediatelyafter the nip between first conveying roller 34 and pinch roller 39 ofconveying portion 2, second sensor 41 is arranged. Furthermore, betweensecond conveying roller 33 and first conveying roller 34, third sensor42 is arranged. Second and third sensors 41 and 42 also functionsimilarly to first sensor 40 aforementioned and detect passing of sheetsP at the positions where the respective light beams cross conveyingroute 101.

The distance between the position where the light beam of first sensor40 crosses conveying route 101 and the position where the light beam ofsecond sensor 41 crosses conveying route 101 is set as indicated below.Namely, the distance is set so that the inter-sensor distance isslightly longer (in this embodiment, 270 [mm]) than the length (in thisembodiment, 250 [mm]) of a sheet longest in length (hereinafter,referred to as a longest sheet) in the conveying direction among sheetsP to be processed by take-out apparatus 100 of this embodiment.

Furthermore, all motors 5, 12, 16, 19, 22, 25, 28, 31, and 37 oftake-out apparatus 100 aforementioned are connected to controller 43 viaa control circuit not drawn. To controller 43, the output terminals, notdrawn, of first to third sensors 40, 41, and 42 aforementioned areconnected and the conveying condition of sheets P is sent to controller43. Furthermore, controller 43 includes internally timer 44 formeasuring the conveying time of sheets P and gap counter 45 for countingthe number of gaps between sheets P. Further, controller 43 functions asdrawing roller 29 and pinch roller 32 aforementioned and as are-separation unit of the present invention. First sensor 40 and secondsensor 41 aforementioned function as an overlapping detector of thepresent invention.

Controller 43 presses floor motor 5 to move floor belt 3 and movesbackup plate 6. By movement of backup plate 6, sheets P put on floorbelt 3 in the standing position are moved toward feed roller 8 in thestacking direction. When sheets P in the moving direction are arrangedat the take-out position and are rotated in contact with feed roller 8,controller 43 rotates feed-out motor 12, rotates feed-out roller 8, andfeeds sheets P at the end in the stacking direction onto conveying route101.

Sheets P fed onto conveying route 101 are conveyed in the forwarddirection by the plurality of motors 17, 23, 29, 33, and 34 installed onthe same side of conveying route 101 as feed out roller 8. At this time,to form appropriate gaps between sheets P taken out continuously andsurely convey free of creases, the feed speed of sheets P by eachroller, that is, the peripheral speed is set so as to slightly increasetoward the downstream side in the conveying direction. Concretely, theperipheral speed of first feed roller 17 is made faster than that offeed-out roller 8, and the peripheral speed of second feed roller 23 ismade faster than that of first feed roller 17, and the peripheral speedof drawing roller 29 is made faster than that of second feed roller 23,and the peripheral speeds of first and second conveying rollers 33 and34 are set to be the same as that of drawing roller 29.

When sheets P fed onto conveying route 101 by feed-out roller 8 areoverlapping sheets and the concerned overlapping sheets pass firstseparation unit SP1, first sheet P is fed in the forward direction byfirst feed roller 17 and second and subsequent sheets P are givenseparation force from first separation roller 20 and are shifted andseparated. The overlapping sheets which pass first separation unit SP1and are not separated completely are further shifted and separated whenpassing second separation unit SP2 and are drawn by drawing roller 29and pinch roller 32 having a peripheral speed slightly faster than thatof second feed roller 23.

Sheets P which pass separation and supply portion 1 and are separatedone by one in this way are conveyed by second conveying roller 33 androller 31 first conveying roller 34 of conveying portion 2 and are fedto a processor not drawn from take-out apparatus 100.

Further, the gaps between sheets P aforementioned are formed by usingfirst sensor 40. Namely, so as to make the gaps between sheets P beforepassing the optical axis of first sensor 40 slightly smaller than thetarget gap, the peripheral speeds of rollers 8, 17, 23, and 29 are set.The time from passing of the rear end of preceding sheet P passing firstsensor 40 in the conveying direction to passing of the front end ofsucceeding sheet P in the conveying direction is measured by timer 44,and the gap between the two is measured from this time, and so as to usethis gap as a target gap, the conveyance of succeeding sheets P isretarded.

When retarding the conveyance of succeeding sheets P, the rotationalspeeds of drawing roller 29 and pinch roller 32 are decreased androllers 8, 17, 23, and 29 on the upstream side in the conveyingdirection are all decelerated. Alternatively, rollers 8, 17, 23, and 29may be stopped or rotated reversely only for a short time.

Next, the re-separation operation when overlapping sheets cannot beseparated by first separation unit SP1 and second separation unit SP2 oftake-out apparatus 100 aforementioned will be explained by referring tothe flow charts shown in FIGS. 2 and 3 and the operation illustrationsshown in FIGS. 4 and 5.

The overlapping sheets which are not separated by first separation unitSP1 and neither separated by second separation unit SP2 are fed toconveying portion 2 after passing first sensor 4 in a state that theyare at least overlapped partially. At this time, it is highly probablethat the overlapping sheets fed to conveying portion 2, after passingfirst separation unit SP1 and second separation unit SP2, are conveyedat least in the shifted state and in such a case, as shown in FIG. 4,the length in the conveying direction is mostly longer than the longestsheet processed by take-out apparatus 100. Therefore, this embodiment,when the length of sheets P fed to conveying portion 2 in the conveyingdirection is longer than the longest sheet, judges that they areoverlapping sheets.

Concretely, as shown at Steps 1 and 2, when two sensors 40 and 41 at adistance more than the longest sheet become dart at the same time (Yesat Step 1 and Yes at Step 2), controller 43, as shown in FIG. 4basically judges that overlapping sheets are conveyed. However, in thiscase, for example, as shown in FIG. 5, a case that between first sensor40 and second sensor 41, there are gaps between sheets P may beconsidered. Therefore, controller 43, when first and second sensors 40and 41 are dark simultaneously and there are no gaps between the two(Yes at Step 3), judges that overlapping sheets are conveyed (Step 4).

The judgment of whether there are gaps of sheets P between first sensor40 and second sensor 41 or not, as shown in FIG. 3, is performed usinggap counter 45 built in controller 43. Namely, controller 43, when firstsensor 40 detects (Yes at Step 11 shown in FIG. 3) that the rear end ofsheet P in the conveying direction passes first sensor 40, counts up gapcounter 45 (Step 12) and when second sensor 41 detects (Yes at Step 13)that the rear end of sheet P in the conveying direction passes secondsensor 41, counts down gap counter (Step 14). By counting by gap counter45 like this, the number of gaps of sheets existing between first sensor40 and second sensor 41 is counted. As a result, controller 43, when gapcounter 45 indicates zero, judges that there are no gaps between sheetsconveyed.

Namely, controller 43, when first and second sensors 40 and 41 are darksimultaneously (Yes at Step 1 and Yes at Step 2) and gap counter 45indicates zero (Yes at Step 3), judges that overlapping sheets areconveyed (Step 4).

Controller 43, when it judges at Step 4 that overlapping sheets areconveyed, stops drawing roller 29 and pinch roller 32 in order tore-separate the concerned overlapping sheets (Step 5). At this time,naturally, controller 43 stops all rollers 8, 17, 23, and 29 ofseparation and supply portion 1. Since first and second sensors 40 and41 are dark simultaneously in this condition, as shown in FIG. 4, thefront ends of the overlapping sheets in the conveying direction areclamped and restricted by the nip between first conveying roller 34 andpinch roller 39 and are fed in the forward direction and the rear endsin the conveying direction are clamped and restricted by the nip betweendrawing roller 29 and pinch roller 32 stopped.

More concretely, as shown in FIG. 4, when two sheets P1 and P2 arepartially overlapped and conveyed, the neighboring part of the front endof first sheet P1 on the side of conveying rollers 33 and 34 in theconveying direction is clamped and restricted by the nip between firstconveying roller 34 and pinch roller 39 and is conveyed in the forwarddirection, and the neighboring part of the rear end of second sheet P2shifted backward from first sheet P1 in the conveying direction isclamped and restricted by the nip between drawing roller 29 and pinchroller 32 stopped, and first sheet P1 and second sheet P2 are drawnapart and, separated.

At this time, when the pressure by the guide plate 38 opposite thesecond conveying roller 33 rotating in contact with the overlapped partof two sheets P1 and P2 is strong, the possibility of second sheet P2being taken out by first sheet P1 is increased, so that as in thisembodiment, it is effective to install the guide plate 38 to make thepress weak.

And, when the rear end of separated and preceding sheet P1 in theconveying direction, as shown in FIG. 5, is detected via second sensor41 or third sensor 42 (Yes at Step 6), controller 43 judges that theconcerned overlapping sheets are separated, restarts the operations ofall rollers 8, 17, 23, and 29 stopped at Step 5 (Step 7), and continuesthe process.

On the other hand, controller 43, when it judges at Step 3 that the gapcounter does not indicate zero, for example, as shown in FIG. 5, judgesthat although two sensors 40 and 41 are dark, there are gaps of sheetsP1 and P2 between sensors 40 and 41, and judges that the concernedsheets are not overlapping sheets (Step 8), and rotates all the rollersas usual (Step 9).

As mentioned above, according to this embodiment, controller 43, whenthe sheets passing second separation unit SP2 are clamped and restrictedby the nip between drawing roller 29 and pinch roller 32, decidesoverlapping, and immediately after deciding overlapping, clamps andstops the rear ends of the overlapping sheets in the conveying directionby drawing roller 29 and pinch roller 32, and re-separates theoverlapping sheets. Therefore, controller 43 serves as drawing roller 29and pinch roller 32 for drawing the sheets from second separation unitSP2, thus can re-separate overlapping sheets which cannot be separatedby first separation unit SP1 and second separation unit SP2, so that byuse of an inexpensive constitution without adding a new apparatusconstitution, overlapping sheets can be surely separated. Therefore, theprocessing capacity of sheets P by take-out apparatus 100 can beenhanced. Particularly, take-out apparatus 100 of this embodiment, aftertrying to separate overlapping sheets by first separation unit SP1 andsecond separation unit SP2, can try separation when drawing theoverlapping sheets from second separation unit SP2 by drawing roller 29and pinch roller 32, can try separation under the re-separation controlaforementioned, can execute the four separation operations in total, andcan separate more surely the overlapping sheets.

In the first embodiment aforementioned, the return timing of the stoppedrollers is set using the detection of the rear ends of sheets in theconveying direction by second sensor 41 or third sensor 42 as a trigger,though third sensor 42 may not be an essential constitution of theinvention. Alternatively, between first sensor 40 and second sensor 41,a plurality of third sensors may be installed.

Further, in consideration of a case that a sheet with a length longerthan the maximum sheet to be processed by take-out apparatus 100 istaken out, to the stop time of the drawing roller at Step 5 shown inFIG. 2, an upper limit may be set. Namely, when a sheet longer than thelongest sheet is decided as an overlapping sheet, in a state that therear end in the conveying direction is stopped by drawing roller 29 andpinch roller 32, second sensor 41 or third sensor 42 will not becomedark for a long time, so that take-out apparatus cannot move to theprocesses at Steps 6 and 7.

Furthermore, in the embodiment aforementioned, when the overlappingsheets are detected, drawing roller 29 and pinch roller 32 are stopped.However, the present invention is not limited to it, and drawing roller29 and pinch roller 32 may be decelerated or rotated reversely, and evenin this case, the similar effect can be produced. Further,“deceleration” in the claims includes stop and reverse rotation.

Next, another embodiment of the present invention will be explained withreference to the flow chart shown in FIG. 6. Further, the constitutionof this embodiment is the same as that of take-out apparatus 100 of theaforementioned embodiment except that it has not second sensor 41 andthird sensor 42, so that here, the explanation of the apparatusconstitution will be omitted.

As shown at Step 1 in FIG. 6, when sheets P are detected via firstsensor 40 (Yes at Step 1); controller 48 counts the passing time bytimer 4 (Step 2). And, controller 43 compares the passing time countedat Step 2 with a reference time (specified value) prepared beforehand(Step 3), and when the counted passing time exceeds the specified value(Yes at Step 3), decides that there are overlapping sheets (Step 4). Thespecified value referred to as here is a value obtained by dividing thelength of the longest sheet in the conveying direction by the conveyingspeed of sheets.

Immediately after deciding overlapping at Step 4, controller 43 stopsdrawing roller 29 and pinch roller 32, also stops feed-out roller 8,first feed roller 17, and second feed roller 23 (Step 5), and counts thestop time (Step 6). The front ends of the overlapping sheets in theconveying direction are fed in the forward direction by first and secondconveying rollers 33 and 34 in this state, so that the overlappingsheets are separated in the same way as with the first embodimentaforementioned. Further, also in this case, each roller may bedecelerated or rotated reversely instead of stopping.

When the stop time counted at Step 6 exceeds the specified valueprepared beforehand (Yes at Step 7), controller 43 judges that theconcerned sheets are separated, restarts the rotation of all rollers 8,17, 23, and 29 which are stopped at Step 5, and continues the process.Further, in this case, the specified value of the stop time is a valueobtained by dividing “length of the longest sheet in the conveyingdirection+target gap” by the conveying speed of sheets.

On the other hand, when first sensor 40 becomes bright before judging atStep 3 that the passing time of sheets P exceeds the specified value,controller 43 judges that the concerned sheets are not overlappingsheets (Step 9), rotates drawing roller 29 and pinch roller 323 as usual(Step 10), and continues the process.

As mentioned above, this embodiment can produce the same effect as thatof the aforementioned embodiment and excludes second and third sensors41 and 42, so that the apparatus constitution can be simplified more andcan provide a more inexpensive take-out apparatus.

Inversely, it is possible to install a sensor on the downstream side offirst sensor 40 in the conveying direction and obtain the return timingof the rollers, thus the processing time can be shortened.

Further, the present invention is not limited straight to theaforementioned embodiments and in the execution stage, within a rangewhich is not deviated from the object thereof, the components can bemodified and materialized. Further, by appropriate combinations of aplurality of components disclosed in the aforementioned embodiments,various inventions can be formed. For example, from all the componentsindicated in the aforementioned embodiments, some may be deleted.Furthermore, components extending over the different embodiments may becombined appropriately.

For example, in the aforementioned embodiments, a case that the lengthof sheets P in the conveying direction is detected and compared with thereference value, thus overlapping sheets are detected is explained.However, the present invention is not limited to it and the thickness ofsheets P is detected, thus overlapping sheets may be detected.

Further, in the aforementioned embodiments, when separating sheets P,frictional force in different directions is acted on overlapped sheets,thus sheets P are shifted and separated. However, the present inventionis not limited to it and it is possible to adsorb one side of sheet P,thereby separate it from overlapping sheets.

Furthermore, in the aforementioned embodiments, a case that in amechanism for conveying sheets P along conveying route 101, independentrollers are used is explained. However, the present invention is notlimited to it and a conveying roller composed of a plurality of rollerswound and stretched may be used in place of it.

The sheet take-out apparatus of the present invention has theaforementioned constitution and operation, so that by use of aninexpensive constitution, overlapping sheets can be separated surely andthe processing capacity can be enhanced.

What is claimed is:
 1. A sheet take-out apparatus comprising: a take-outunit adapted to take out a plurality of sheets in a stacked state one byone on a conveying route; a separation unit adapted to shift andseparate overlapping sheets taken out by the take-out unit on theconveying route as a preceding sheet and a succeeding sheet, theseparation unit being arranged downstream from the take-out unit; anoverlapping detector adapted to detect overlapping sheets which have notbeen separated by the separation unit; and a re-separation unitconfigured to clamp and stop, decelerate, or reversely rotate a rear endof the succeeding sheet detected by the overlapping detector along aconveying direction to re-separate the overlapping sheets, there-separation unit including: a drawing roller and a second pinch rollerarranged downstream from the separation unit to draw out the sheet fromthe separation unit, and a conveying roller arranged downstream from thedrawing roller and the second pinch roller, the conveying roller beingarranged to receive a front end of the preceding sheet and to convey thepreceding sheet, a second conveying roller rotating in contact with thesheets drawn from the separation unit by the drawing roller and thesecond pinch roller; and a compressing member which is arranged oppositeto the second conveying roller via the conveying route and compressesthe sheets against the second conveying roller, wherein there-separation unit operates such that the rotational speed of thedrawing roller is stooped, decelerated, or reversely rotated while thedrawing roller and the second pinch roller clamps the rear end of thesucceeding sheet, and wherein the compressing member clamps the sheetbetween the compressing member and the second conveying roller withforce weaker than clamping force by the drawing roller and the secondpinch roller.
 2. The sheet take-out apparatus according to claim 1,wherein the compressing member is formed by bending a platy member madeof resin.
 3. A sheet take-out apparatus comprising: a take-out unitadapted to take out a plurality of sheets in a stacked state one by oneon a conveying route; a separation unit adapted to shift and separateoverlapping sheets taken out on the conveying route as a preceding sheetand a succeeding sheet; an overlapping detector adapted to detectoverlapping sheets which are not separated by the separation unit; and are-separation unit provided at a downstream from the separation unit andadapted to clamp and stop, decelerate, or reversely rotate a rear end ofthe succeeding sheet detected by the overlapping detector in a conveyingdirection and re-separate the overlapping sheets, the re-separation unitincluding a first conveying roller and a first pinch roller adapted toreceive a front end of the preceding sheet passing the separation unitin the conveying direction, and a drawing roller and a second pinchroller adapted to have their rotational speed stop, decelerate, orreversely rotate from a predetermined speed in a state where the rearend of the succeeding sheet is clamped by the drawing roller and thesecond pinch roller, wherein the overlapping detector is adapted todetect the overlapping sheets which are clamped and restricted by a nipbetween the drawing roller and the second pinch roller; wherein theoverlapping detector includes a first sensor arranged to detect thesheets immediately after the nip of the drawing roller and the secondpinch roller in the conveying direction of the sheets and a secondsensor arranged to detect the sheets at a position away from the firstsensor on a downstream side in the conveying direction, the distancebetween the first and second sensors exceeding the length of a longestsheet; and a controller adapted to judge an overlapping of the sheets ifthe second sensor detects a sheet while, at the same time, the firstsensor detects a sheet and if there are no gaps between the rear end ofthe preceding sheet and the front end of the succeeding sheet betweenthe first and second sensors; and wherein the controller includes a gapcounter adapted to count a gap between the sheets, when the first sensordetects that the rear end of a sheet in the conveying direction pass thefirst sensor, counting up the gap counter, and when the second sensordetects that the rear end of the sheet in the conveying direction passthe second sensor, counting down the gap counter, and when the first andsecond sensors detect simultaneously the sheets and a value of the gapcounter is zero, judging that overlapping of sheets occurs.
 4. The sheettake-out apparatus according to claim 3 further comprising: a speedcontroller adapted to return the rotational speeds of the drawing rollerand the second pinch roller from the deceleration to the predeterminedspeed when the second sensor detects passing of the rear ends of thesheets in the conveying direction.
 5. The sheet take-out apparatusaccording to claim 3 further comprising: a third sensor on thedownstream side of the first sensor and upstream side of the secondsensor in the conveying direction, and when the third sensor detectspassing of the rear ends of the sheets in the conveying direction, isadapted to return the rotational speeds of the drawing roller and thesecond pinch roller from the deceleration to the predetermined speed.